1. Technical Field
The present invention relates to a technique for displaying a right-eye image and a left-eye image mutually having parallax to provide a stereoscopic effect to an observer.
2. Related Art
Hitherto, display devices displaying an image using illumination light emitted from an illumination device have been suggested. For example, an illumination device using an alternating current driving type discharge lamp is used for a projection type display device displaying an image by projecting display light modulated in accordance with a display image on a projection surface. JP-T-2002-533884 and JP-A-2005-353343 disclose techniques for stabilizing lighting (discharging) by overlapping pulses P with an alternating driving current supplied to a discharge lamp, as shown in FIG. 6.
In the configuration disclosed in JP-T-2002-533884 and JP-A-2005-353343, in which the pulses P are overlapped with the driving current of the discharge lamp, as shown in FIG. 6, the intensity of display light (illumination light) emitted from the illumination device is varied (pulsated) at the time points of the pulses P. The instantaneous variation (hereinafter, referred to as “intensity variation”) v of the display light causes deterioration (display spot) in display quality, as described below.
In the projection type display device, a plurality of pixels arranged in a matrix form is selected sequentially in a row unit and image signals corresponding to designated gray scales are supplied to the pixels of the selected rows and are maintained. The plurality of pixels each includes, for example, a transistor that controls a liquid crystal element. The electric characteristics (for example, the degree of current leak) of each transistor forming the pixel are varied in accordance with the intensity of illumination light.
As shown in FIG. 7, when the intensity variation v occurs in the display light from the illumination device during a horizontal scanning period of selecting the m-th row and, for example, even when the gray scale common to all the pixel circuits is designated, an error occurs between the voltage values of the image signal maintained in the respective pixels of the m-row and the image signal maintained in the respective pixels of the other rows. That is, an observer may recognize a horizontal line-shaped display spot (in the m-th row) where the gray scale is different from that of the periphery. Specifically, when the intensity variation v (overlap of the pulses P) and the vertical scanning of the projection type display device are synchronized with each other, the line-shaped display spot is normally located in a predetermined row (for example, the m-th row). When the intensity variation of the display light and the vertical scanning are not synchronized with each other, the line-shaped display spot is moved over time (so-called scroll noise).
In the above description, the intensity variation v of the display light has been exemplified to stabilize the discharge of the discharge lamp. However, the same problem may arise even when the intensity of the display line is made to be instantaneously varied (or inevitably varied) due to the reasons other than the stabilization of the discharge.